This invention relates to apparatus for dyeing web carpets and the like in general and more particularly to an apparatus in which dye is applied to the carpet by means of a roll rotating in a trough with the dye liquid scraped therefrom by a doctor blade and in which the web passes horizontally beneath the trough in close proximity thereto.
Devices for the application of dye or the like to a web of material such as a carpet which utilize a roll rotating in a trough to pick up liquid which is scraped off by a doctor blade and then allowed to flow down the blade and drop onto the web of material are known. In such devices the trough, roller and doctor blade are all disposed above the web of material to be treated. Apparatus of this general type is disclosed in U.S. Pat. Nos. 3,964,860 and 4,033,153. Although, in the presentation in these patents, the web is shown as passing beneath the trough horizontally, in actual practice such is not usually the case. In actual practice, the carpet or other web normally approaches the applicator apparatus from below travelling in a generally vertical direction and is deflected to the horizontal right before passing beneath the doctor blade from which the dye liquid flows. The primary reasons for this arrangement is to permit adequate support of the roll and trough. It must be kept in mind that the trough extends across the full width of the carpet which can be as much as 15 feet. Furthermore, it extends rearward for a distance and contains a relatively large amount of liquid. Because of this, it requires good support, particularly when one considers the types of forces which will be applied to the trough because of the roll rotation.
It should also be noted that, in the aforementioned U.S. Pat. No. 3,964,860, which shows a plurality of applicators beneath which a basically horizontal web runs, there are other means between the doctor blade and carpet so that the troughs are raised up. This allows additional room for supporting structures.
However, there are also applications where it is desired to maintain the web horizontal at all times and where, with a short doctor blade, it is desired to have the doctor blade in close proximity to the web. It will be evident to those skilled in the art that having the doctor blade a long distance from the web, or even having a relatively long doctor blade, can result in uneven flow. What is desired is that the film of liquid from the doctor blade be spread evenly on the web. This requires that the doctor blade be relatively short and that it be relatively close to the web to avoid the formation of streams of liquid rather than a film of liquid.
In situations where the web must be horizontal and where these other conditions, i.e., a relatively narrow doctor blade and close proximity of the edge of the doctor blade to the web are required, the previously used supporting structure which was disposed vertically below the trough cannot be used. Thus, a need arises for applicating apparatus, in which a wide trough containing a roll from which liquid is scraped by a relatively narrow doctor blade and deposited on a carpet running horizontally therebelow, which is adequately supported without the need for large vertical supporting structures.